Red Tiger Dumpling House is at 1320 Stony Brook Road. The modest-looking little place offers authenticity at bargain prices. There is a fine selection of dumplings, along with a panoply of Chinese dishes, most from Shanghai, Beijing and points north. Fans of the shanghai phenomenon known as the soup dumpling can rejoice in the dumpling house. Also on the menu: Pork and vegetable dumplings, beef stew noodle soup, Cumin beef, and a vegetarian choice, Shredded potato with hot pepper.....